Lionel Messi of Barcelona went up against his fellow Argentine Sergio Aguero of Manchester City in the second leg of the last 16 Champions League clash between the two sides at the Camp Nou. Aguero had to be substituted at halftime after suffering a hamstring injury.

Manchester City manager Manuel Pellegrini was forced to sit from the stands after being handed a touchline ban by UEFA. The Chilean made disparaging remarks about Swedish referee Jonas Eriksson following the first leg defeat by Barcelona.

Messi broke the deadlock to give Barcelona a 1-0 lead with a classy finish. That goal was the 67th of his Champions League career.

City's Pablo Zabaleta was shown a second yellow card and was then sent off by referee Stephane Lannoy after complaining about the failure to award his side a penalty. Edin Dzeko was sent tumbling by Gerard Pique but the referee waved play on.

James Milner looks decimated after Dani Alves seals the win for Barcelona. Vincent Kompany had leveled the game at 1-1 before Alves struck. Barcelona went through 3-1 on aggregate.

Trailing 4-0 from the first leg, Bayer Leverkusen took a shock early lead at Paris Saint-Germain when Sidney Sam headed home a shock opener.

PSG leveled through Marquinhos on 13 minutes to restore their four-goal aggregate lead and tie the game up at 1-1. Ezequiel Lavezzi netted a winner for the home side in the second half.

(CNN) -- Barcelona may not be the force it once was -- but it still had too much for Manchester City.

City, which has now exited both the FA Cup and Champions League in the past week, was always going to find life difficult after losing the first leg of its Champions League last-16 tie.

Trailing by two goals and with the knowledge that no club has ever managed to progress after suffering a 2-0 defeat at home in the first leg of the competition, City at least gave it a real go in a pulsating contest at the Camp Nou.

With manager Manuel Pellegrini sat in the stands after being handed a touchline ban following his disparaging remarks about Swedish referee Jonas Eriksson, who presided over the first leg, City was left in the hands of assistant Ruben Cousillas.

Not that there was much Cousillas could do as Barcelona began to turn the screw.

First, the home side felt it should have been awarded a penalty when Messi went down under the challenge of Joleon Lescott but referee Stephane Lannoy waved away the appeals.

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If that decision was marginal, what followed was hugely fortunate as the assistant referee deprived Barcelona of what would have been a perfectly legitimate goal.

Messi found Xavi and when the midfield maestro slipped in Jordi Alba, the full-back crossed for Neymar to tap the ball into the empty net.

Unfortunately for Barcelona, the offside flag had been raised, despite Alba clearly being in an onside position.

Having survived the early scare, City slowly found their feet and should have taken the lead four minutes before the interval.

Yaya Toure, formerly of Barcelona, picked out David Silva and when the Spaniard's sublime flick found Samir Nasri, the City midfielder could only shoot straight at Victor Valdes.

The second half provided more enthralling action with Messi coming within inches of breaking the deadlock after jinking his way into the penalty area before smashing an effort against the post.

At the other end, Edin Dzeko, on as a halftime substitute for the injured Sergio Aguero, sent a looping header towards goal which was brilliantly clawed away by Valdes with the ball seemingly destined for the corner.

Pablo Zabaleta then fired wide as City threatened to plunder the goal that their play had deserved.

As City pushed forward in search of that elusive opener, Barcelona began to make the most of the space left behind.

And it came as little surprise when Messi finally broke through, clipping the ball past Joe Hart to score his 67th Champions League goal.

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There was still more drama to come with a little over 12 minutes remaining when Dzeko appeared to be blatantly fouled inside the penalty area by Gerard Pique -- but referee Lannoy disagreed.

Such was City's anger that Zabaleta was shown a second yellow card and promptly dismissed for voicing his frustration.

City did net an equalizer through Kompany with a minute of normal time remaining to salvage some pride.

But Barcelona refused to be denied and Dan Alves netted a late winner, firing home from Andres Iniesta's pass to secure victory.

"It was a very tight game against a world class team," Barcelona's Cesc Fabregas told Sky Sports.

"It was a great result to win 2-0 over there and today it was tough.

"We created a lot of chances, we had a goal which was onside ruled out and could have had a penalty.

"We go home happy. The last couple of games have not made us happy, we had some negative results but we have to be proud of today's result.

"Everything is good at the club. We are in the final of the cup, we are four points behind in the league and in the last eight of the Champions League. A lot of teams would swap."

Messi, who scored his 28th goal of the season, believes this result proves Barcelona is on the way back to finding its best form.

Barca, which sits third in La Liga, faces Osasuna this weekend before traveling to Madrid for 'El Clasico' on March 23.

"I think tonight we got back to being the Barcelona that we all want to see and we were able to beat a very tough opponent," he told Canal Plus.

"I don't know if the criticism (in the media after the La Liga defeat to Valladolid) was over the top. We are the first to criticize ourselves and we didn't play the way we should have done there.

"We don't let the criticism affect us and we just focus on ourselves and try to turn things around and that's what we did tonight, I think."